Oates said the gunman wore a gas mask and a ballistic helmet and vest, as well as leg, groin and throat protectors. He said he bought four guns from local gun shops in the last 60 days and 6,000 rounds of ammunition, including a drum magazine that could fire 50 to 60 rounds per minute.

"My understanding is that all the weapons that he possessed, he possessed legally. And all the clips that he possessed, he possessed legally. And all the ammunition that he possessed, he possessed legally," Oates said at a press conference Friday.